1. Field of the Invention
The present invention generally relates to an angular velocity sensor and a method for fabricating the same and more particularly, to an angular velocity sensor having a tuning-fork vibrator and a method for fabricating the same.
2. Description of the Related Art
An angular velocity sensor is a sensor that senses an angular velocity in rotation, and is used in systems for image stabilization of camera, for automotive navigation, for stability control of vehicles or postures of robots, and the like. Japanese Patent Application Publication No. 2001-165664 discloses an angular velocity sensor having a tuning-fork vibrator and a technique to improve drive efficiency by a composition of electrodes provided on the tuning-fork vibrator which is made by putting together two tuning-fork vibrators directly so that each of generated electric charges of the tuning-fork vibrators is opposite each other. Japanese Patent Application Publication No. 2004-301510 discloses an angular velocity sensor having a tuning-fork vibrator and a technique to sense angular velocities about a plurality of axes. In order to realize this technique, it needs to put some weight on upper parts of arms of the tuning-fork vibrator in order to increase inertial force.
Tuning-fork vibrators make a progress in downsizing in accordance with downsizing of angular velocity sensors. However, downsized tuning-fork vibrators have a problem to decrease drive efficiency and thus amplitude in driving vibration is small. In this case, amplitude in detecting vibration generated by Coriolis force is relatively small when an angular velocity is applied, and it is thus difficult to sense angular velocity.